German chancellor Angela Merkel delivered her strongest statement yet in support of Jean-Claude Juncker’s bid to become the next president of the European Commission, dealing a fresh blow to British prime minister David Cameron, who is attempt to block the accession of the former Luxembourg prime minister to the European Union’s top job.

Speaking at a joint press conference yesterday in Sweden, following a “mini summit” of four EU leaders, the Dr Merkel said “threats” were “not part of the European spirit”, a barely veiled rebuff to Mr Cameron, who has hinted that the appointment of Mr Juncker could significantly affect Britain’s support for the EU project ahead of a planned referendum on Britain’s membership of the EU.

“I have said that for me Jean-Claude Juncker is the candidate for the office of commission president and that I want to have him as the commission president,” the German chancellor said. But, standing alongside Dr Merkel, Mr Cameron reiterated his opposition to the election process.

“The decision about whether to stay in Europe will be for the British people in a referendum by the end of 2017,” he said.

“Obviously the approach that the EU takes between now and then will be very important. If we can achieve reforms, if we can demonstrate openness, competitiveness, flexibility, less interference, reform – if people are capable of taking the EU forward in that direction, that will be helpful.

“Obviously if the EU doesn’t go in that direction that would be very unhelpful. I think it is very plain and very obvious.”

Mr Cameron already has the support of the Sweden’s prime minister Fredrik Reinfeldt and Dutch prime minister Mark Rutte, who travelled to Dublin for talks with Taoiseach Enda Kenny following the meeting.

While declining to comment on the specifics of Mr Juncker’s candidacy, both have expressed opposition to the Spitzenkandidat concept, which proposes that the candidate from the largest political group in the European Parliament should become the next commission president.

Labour position

Britain also solidified its position further as the Labour party confirmed it, too, opposed Mr Juncker. “The nominee for European Commission president is ultimately a decision for the European Council, including David Cameron,” a Labour Party spokesman said. “Labour will not support Jean-Claude Juncker as a candidate for president of the European Commission. Should Mr Juncker be put before the European Parliament, Labour MEPs would vote against him. The message from the European elections was clear – that we need reform in Europe . . . Mr Juncker’s record shows he would make these reforms more difficult.”

The British Labour Party, which is a member of the second largest Socialists and Democrats (S&D) group in the European Parliament, also opposed the S&D’s candidate to become the president, Martin Schulz.

Dr Merkel’s comments yesterday come as a further boost to the Juncker camp, which has strenuously denied reports the former Luxembourg premier and euro group head would withdraw from the process.

Dr Merkel, who initially indicated lukewarm support for the process, came under increasing pressure last week from her junior coalition partner, the Social Democrats and the German media to endorse the process.